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Abstract:

In an hydraulic pressure supply apparatus for a transmission having an
input shaft connected to a drive shaft of a prime mover mounted on a
vehicle through a torque converter with a lockup clutch, it is configured
to have a hydraulic pump drawing up and discharging operating oil; a
regulator valve regulating discharged pressure to a line pressure; first
and second switching valves supplying hydraulic pressure to the first and
second clutches; a first hydraulic control valve supplying the regulated
line pressure to the lockup clutch; a third switching valve connected to
an output port of the first hydraulic control valve; and first and second
electromagnetic valves connected to operating ports of the first, second
and third switching valves and adapted to switch among the first, second
and third switching valves upon being energized and deenergized.

Claims:

1. An hydraulic pressure supply apparatus for a transmission having an
input shaft connected to a drive shaft of a prime mover mounted on a
vehicle through a torque converter with a lockup clutch, first and second
secondary input shafts installed in parallel with the input shaft, an
output shaft connected to a wheel, first and second clutches connect the
input shaft to the first and second secondary input shafts upon being
supplied with hydraulic pressure, a plurality of pairs of gear groups
installed at the first or second secondary input shaft, and a gear
selecting mechanism adapted to select one of the plurality of the pairs
of the gear groups upon being supplied with hydraulic pressure to
establish an odd-numbered speed or even-numbered speed, the transmission
changing an output of the prime mover in speed through the established
speed and transmitting it to the wheel through the output shaft,
comprising: a hydraulic pump adapted to be driven by the prime mover and
to draw up operating oil from a hydraulic pressure source and discharge
the operating oil; a regulator valve adapted to regulate discharged
pressure discharged from the hydraulic pump to a line pressure; first and
second switching valves adapted to supply hydraulic pressure to the first
and second clutches; a first hydraulic control valve adapted to supply
the regulated line pressure to the lockup clutch; a third switching valve
connected to an output port of the first hydraulic control valve; and
first and second electromagnetic valves connected to operating ports of
the first, second and third switching valves and adapted to switch among
the first, second and third switching valves upon being energized and
deenergized.

2. The apparatus according to claim 1, wherein one of the first and
second electromagnetic valves is energized and deenergized to change an
operation mode of the transmission among a first operation mode in which
shifting is possible with the odd-numbered speed and the even-numbered
speed in a forward range, a second operation mode in which shifting is
possible with the odd-numbered speed or the even-numbered speed in the
forward range, and a third operation mode in which the vehicle is driven
in a range other than the forward range.

3. The apparatus according to claim 1, wherein one of the first and
second electromagnetic valves is energized and deenergized to supply
hydraulic pressure to the lockup clutch through the first hydraulic
control valve and stop the supply.

4. The apparatus according to claim 1, wherein the input shaft includes
first and second input shafts connected to the drive shaft of the prime
mover through the first and second clutches, respectively, and the output
shaft includes at least one output shaft installed in parallel with the
first and second input shafts, and the transmission includes a dual
clutch type automatic transmission having: a plurality of speeds to be
established through gears installed between the first and second input
shafts and the output shaft, the plurality of the speeds being
constituted by at least four sets; a synchronizing mechanism
corresponding to each of the four sets, adapted to be operated upon being
supplied with hydraulic pressure to move from a neutral position to
select one of the speeds that constitutes a corresponding one of the four
sets so as to engage a corresponding one of the gears to one of the first
and second input shafts and the output shaft; and a hydraulic pressure
supply control unit including first and second pressure regulators
interposed at a hydraulic pressure circuit connecting the hydraulic
pressure source and the synchronizing mechanism, each adapted to
selectively supply hydraulic pressure to the synchronizing mechanism to
move such that the output of the prime mover is outputted from one of the
first and second input shafts to the output shaft through the selected
speed.

Description:

BACKGROUND

[0001] 1. Technical Field

[0002] An embodiment of the invention relates to a hydraulic pressure
supply apparatus for a transmission, particularly to a hydraulic pressure
supply apparatus for a vehicle transmission that can disengage (release)
a lockup clutch of a torque converter with the simple structure.

[0003] 2. Background Art

[0004] When a transmission has a torque converter equipped with a lockup
clutch, under a predetermined vehicle driving condition, unless the
lockup clutch is promptly disengaged, a prime mover such as an engine
stalls. To cope with it, a conventional technique is configured to
install a special device for releasing the lockup clutch, as taught, for
example, by Japanese Laid-Open Patent Application No. 2009-92213 ('213).

SUMMARY

[0005] The technique of the reference is configured as above to promptly
disengage the lockup clutch under the predetermined vehicle driving
condition, yet it requires the special device, the cost rises
disadvantageously.

[0006] Further, in the reference, the manual valve is installed for
switching a hydraulic passage in response to the operation of a range
selector manipulated by the operator. However, the manual valve needs to
be set with at least four positions of D, P, R and N and it leads to the
increase in its valve length, while, since it is connected with a lever
installed in a vehicle interior, it degrades the layout of components in
a transmission case. Thus, due to the installment of the manual valve,
the transmission can not have the compact structure.

[0007] An object of an embodiment of the invention is therefore to
overcome the foregoing drawbacks by providing a hydraulic pressure supply
apparatus for a transmission that can disengage a lockup clutch of a
torque converter promptly and easily, while enabling the transmission to
operate in a range selected by the operator without the manual valve.

[0008] In order to achieve the object, this invention provides an
hydraulic pressure supply apparatus for a transmission having an input
shaft connected to a drive shaft of a prime mover mounted on a vehicle
through a torque converter with a lockup clutch, first and second
secondary input shafts installed in parallel with the input shaft, an
output shaft connected to a wheel, first and second clutches connect the
input shaft to the first and second secondary input shafts upon being
supplied with hydraulic pressure, a plurality of pairs of gear groups
installed at the first or second secondary input shaft, and a gear
selecting mechanism adapted to select one of the plurality of the pairs
of the gear groups upon being supplied with hydraulic pressure to
establish an odd-numbered speed or even-numbered speed, the transmission
changing an output of the prime mover in speed through the established
speed and transmitting it to the wheel through the output shaft,
comprising: a hydraulic pump adapted to be driven by the prime mover and
to draw up operating oil from a hydraulic pressure source and discharge
the operating oil; a regulator valve adapted to regulate discharged
pressure discharged from the hydraulic pump to a line pressure; first and
second switching valves adapted to supply hydraulic pressure to the first
and second clutches; a first hydraulic control valve adapted to supply
the regulated line pressure to the lockup clutch; a third switching valve
connected to an output port of the first hydraulic control valve; and
first and second electromagnetic valves connected to operating ports of
the first, second and third switching valves and adapted to switch among
the first, second and third switching valves upon being energized and
deenergized.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above and other objects and advantages of an embodiment of the
invention will be more apparent from the following description and
drawings in which:

[0010] FIG. 1 is an overall schematic view of a hydraulic pressure supply
apparatus for a transmission according to an embodiment of this
invention;

[0013] FIG. 4 is a table showing operation modes of the transmission shown
in FIG. 1;

[0014] FIG. 5 is a set of explanatory views showing the characteristics of
outputs relative to supply current of a hydraulic control valve shown in
FIG. 2 and the like; and

[0015] FIG. 6 is a set of explanatory views similarly showing the
characteristics of outputs relative to supply current of the hydraulic
control valve shown in FIG. 2 and the like.

DESCRIPTION OF EMBODIMENT

[0016] A hydraulic pressure supply apparatus for a transmission according
to an embodiment of the present invention will now be explained with
reference to the attached drawings.

[0017] FIG. 1 is an overall schematic view of a hydraulic pressure supply
apparatus for a transmission according to an embodiment of this
invention, FIG. 2 is a hydraulic pressure circuit diagram showing details
of the apparatus shown in FIG. 1, FIG. 3 is an enlarged view partially
showing the hydraulic pressure circuit diagram of FIG. 2 and FIG. 4 is a
table showing operation modes of the transmission shown in FIG. 1.

[0019] The transmission T is installed with an even-numbered speed input
shaft (hereinafter called "even input shaft") 14 connected via a torque
converter 12 to a drive shaft 10a connected to a crankshaft of an engine
(prime mover) 10, and an odd-numbered speed input shaft (hereinafter
called "odd input shaft") 16 in parallel with the even input shaft 14.
The engine 10 comprises, for example, a spark-ignition, gasoline internal
combustion engine.

[0020] The torque converter 12 has a pump impeller 12b fixed to a drive
plate 12a that is directly connected to the drive shaft 10a of the engine
10, a turbine runner 12c fixed to the even input shaft 14, and a lockup
clutch 12d, so that the driving force (rotation) of the engine 10 is
transmitted to the even input shaft 14 through the torque converter 12.

[0021] An idle shaft 18 is installed in parallel with the even and odd
input shafts 14, 16. The even input shaft 14 is connected to the idle
shaft 18 via gears 14a, 18a and the odd input shaft 16 to the idle shaft
18 via gears 16a, 18a, whereby the even and odd input shafts 14, 16 and
idle shaft 18 are rotated by the rotation of the engine 10.

[0022] Further, a first secondary input shaft 20 and second secondary
input shaft 22 are installed on outer peripheries of the odd and even
input shafts 16, 14 to be coaxially therewith and rotated relative
thereto, respectively.

[0023] The odd input shaft 16 and the first secondary input shaft 20 are
interconnected by a first clutch 24, while the even input shaft 14 and
the second secondary input shaft 22 by a second clutch 26. The first and
second clutches 24, 26 comprise hydraulically-operated multi-plate wet
clutches.

[0024] An output shaft 28 is disposed between the even and odd input
shafts 14, 16 in parallel therewith. The even and odd input shafts 14,
16, idle shaft 18 and output shaft 28 are rotatably supported by bearings
30.

[0026] The output shaft 28 is fixed with a first-second speed driven gear
48 to be meshed with the first-speed and second-speed drive gears 32, 40,
a third-fourth speed driven gear 50 to be meshed with the third-speed and
fourth-speed drive gears 34, 42, fifth-sixth speed driven gear 52 to be
meshed with the fifth-speed and sixth-speed drive gears 36, 44, and a
seventh-eighth speed driven gear 54 to be meshed with the seventh-speed
and eighth-speed drive gears 38, 46.

[0027] The idle shaft 18 rotatably supports an RVS (reverse) idle gear 56
that is to be meshed with the first-second speed driven gear 48 fixed at
the output shaft 48. The idle shaft 18 is connected with the RVS idle
gear 56 through an RVS clutch 58.

[0028] The RVS clutch 58 comprises a hydraulically-operated multi-plate
wet clutch similarly to the first and second clutches 24, 26, but the
diameter and the number of friction plates of the RVS clutch 58 are
smaller than those of the clutches 24, 26. In the operation mode table in
FIG. 4, the first and second clutches 24, 26 are indicated by "CL1" and
"CL2" and the RVS clutch 50 by "RVS" in the "CLUTCH" column

[0030] The even input shaft 14 is disposed with a second-fourth speed
synch (synchronizing) mechanism 64 that selectively engages the
second-speed drive gear 40 or fourth-speed drive gear 42 with the second
secondary input shaft 22 and with a sixth-eighth speed synch
(synchronizing) mechanism 66 that selectively engages the sixth-speed
drive gear 44 or eighth-speed drive gear 46 with the second secondary
input shaft 22. The synch mechanisms 60, 62, 64, 66 engage the gears with
the shafts while synchronizing the rotation therebetween.

[0031] When the first clutch 24 or the second clutch 26 is engaged, the
driving force of the engine 10 is transmitted via the odd input shaft 16
to the first secondary input shaft 16 or via the even input shaft 14 to
the second secondary input shaft 22, and then transmitted to the output
shaft 28 through relevant ones of the aforementioned drive gears and
driven gears.

[0032] When the vehicle is to be moved backward, the driving force of the
engine 10 is transmitted to the output shaft 28 through the even input
shaft 14, gear 14a, gear 18a, RVS clutch 58, idle shaft 18, RVS idle gear
56 and first-second speed driven gear 48.

[0033] The output shaft 28 is connected to a differential mechanism 72
through a gear 70 and the differential mechanism 72 is connected to
wheels 76 through drive shafts 74.

[0035] The hydraulic pressure supply unit 80 will be explained with
reference to FIG. 2.

[0036] In the hydraulic pressure supply unit 80, discharged pressure
(hydraulic pressure) of operating oil ATF that is pumped up (drawn) from
a reservoir 80a through a strainer 80b by a hydraulic pump (oil transfer
pump) 80c, is regulated (decreased) to a line pressure by a regulator
valve 80d.

[0037] Although not illustrated, the hydraulic pump 80c is connected to
the pump impeller 12b of the torque converter 12 through a gear so that
the hydraulic pump 80c is driven by the engine 10.

[0038] The regulated line pressure is sent to input ports of first,
second, third and fourth linear solenoid valves (hydraulic control valves
(electromagnetic control valves)) 80f, 80g, 80h, 80i through a hydraulic
passage 80e. In a CLUTCH column and SERVO column of the operation mode
table in FIG. 4, the first to fourth linear solenoid valves 80f, 80g,
80h, 80i are indicated by A, B, C and D, respectively.

[0039] Each of the first to fourth linear solenoid valves 80f, 80g, 80h,
80i is configured to have the characteristics in which a spool is
displaced in proportion to supplied current so as to change output
hydraulic pressure to be outputted from its output port linear, and is of
N/C (normally-closed) type in which the spool is displaced to the open
position upon being supplied with current (being energized).

[0040] The output port of the first linear solenoid valve 80f is connected
to the first clutch 24 of the odd input shaft 16 through a first clutch
shift valve 80j, while the output port of the second linear solenoid
valve 80g is connected to a piston chamber of the second clutch 26 of the
even input shaft 14 through a second clutch shift valve 80k.

[0041] When the first or second clutch 24, 26 is engaged (made ON) upon
being supplied with hydraulic pressure, the first or second secondary
input shaft 20 or 22 is fastened to the odd or even input shaft 16 or 14.
In contrast, when hydraulic pressure is discharged so that the first or
second clutch 24, 26 is disengaged (made OFF), the connection between the
first or second secondary input shaft 20 or 22 and the odd or even input
shaft 16 or 14 is cut off.

[0042] The output port of the third linear solenoid valve 80h is connected
to a fifth-speed piston chamber 62a and seventh-speed piston chamber 62b
of the fifth-seventh speed synch mechanism 62 and also to a second-speed
piston chamber 64a and fourth-speed piston chamber 64b of the
second-fourth speed synch mechanism 64 through the first clutch shift
valve 80j and first and second servo shift valves 80n, 80o.

[0043] The output port of the fourth linear solenoid valve 80i is
connected to a first-speed piston chamber 60a and third-speed piston
chamber 60b of the first-third speed synch mechanism 60 and also to a
sixth-speed piston chamber 66a and eighth-speed piston chamber 66b of the
sixth-eighth speed synch mechanism 66 through the second clutch shift
valve 80k, the first servo shift valve 80n and a third servo shift valve
80p.

[0044] In the synch mechanisms, the above piston chambers 60a and 60b, 62a
and 62b, 64a and 64b and 66a and 66b are arranged to face each other, and
pistons of each pair are interconnected by a shared piston rod. The
piston rod of each pair is connected to a shift folk 60c, 62c, 64c, 66c.

[0045] The shift folk 60c, 62c, 64c, 66c is fixed on a folk shaft (not
shown). Detents (not shown) are provided at the folk shaft at positions
corresponding to the neutral position and right and left gear-in
(engaging) positions. When the shift folk 60c, 62c, 64c, 66c is at the
neutral or gear-in position, the position is retained by the detent,
thereby making hydraulic pressure supply unnecessary.

[0046] In the synch mechanism 60, 62, 64, 66, as shown in FIG. 2, the
shift folk 60c, 62c, 64c, 66c is connected to a circular sleeve 60d, 62d,
64d, 66d. The inner periphery of the sleeve 60d, 62d, 64d, 66d
accommodates a hub 60e, 62e, 64e, 66e that is spline-coupled to the first
or second secondary input shaft 20, 22 to be movable in the axial
direction.

[0047] The first-speed and third-speed drive gears 32, 34 are installed on
either side of the hub 60e through a blocking ring 60f, the fifth-speed
and seventh-speed drive gears 36, 38 on either side of the hub 62e
through a blocking ring 62f, the second-speed and fourth-speed drive
gears 40, 42 on either side of the hub 64e through a blocking ring 64f,
and the sixth-speed and eighth-speed drive gears 44, 46 on either side of
the hub 66e through a blocking ring 66f. Springs are each provided near
the blocking rings 60f, 62f, 64f, 66f.

[0048] The blocking rings 60f, 62f, 64f, 66f are formed with splines while
the associated drive gears are formed with dog teeth. Further, the
blocking rings 60f, 62f,64f, 66f are formed with tapered cones while the
associated drive gears are formed with corresponding tapered cones.

[0049] Further explanation will be made taking the synch mechanism 60 as
an example. Since it is configured as described above, when hydraulic
pressure is supplied to one of the piston chambers, e.g., the third-speed
piston chamber 60b so that the first-speed piston chamber 60a facing
thereto and the piston rod connected to the piston chamber 60a are moved
forward right in FIG. 2, the sleeve 60d connected to the piston rod
through the shift folk 60c is moved in the same direction and contacts
the spring to urge the blocking ring 60f toward the first-speed drive
gear 32 through the spring.

[0050] When the sleeve 60d is moved further forward, the spline of the
sleeve 60d contacts the spline of the blocking ring 60f and the tapered
cone of the blocking ring 60d contacts the tapered cone of the gear 32,
whereby torque is induced by the frictional force.

[0051] When the sleeve 60d is still further moved, the rotation of the
sleeve 60d and that of gear 32 are synchronized due to the torque and the
sleeve 60d is moved forward with its spline pushing the spline of the
blocking ring 60f. Subsequently, when the torque disappears due to the
synchronized rotation, the sleeve 60d is moved still further forward so
that its spline is integrally engaged with the spline of the blocking
ring 60f, and moved still further forward to be integrally engaged with
the dog teeth of the gear 32. Thus the gear-in (engaging) condition is
established.

[0052] The other synch mechanisms 62, 64, 66 are configured in the same
manner. Specifically, when the sleeve 62d, 64d, 66d is axially moved
(shifted) from the center (corresponding to the neutral position) to the
in-gear position, it is engaged with the dog teeth of corresponding one
of the drive gears 36, 38, 40, 42, 44, 46 as synchronizing their
rotation, so as to connect the drive gear 36, etc., to the first or
second secondary input shaft 20, 22.

[0053] The line pressure of a hydraulic passage 80q regulated by
controlling an amount of operating oil discharged from a pressure
regulation port 80d1 of the regulator valve 80d, is sent to input ports
of first to fifth solenoid valves (hydraulic control valves
(electromagnetic valves)) 80r, 80s, 80t, 80u, 80v.

[0054] Those solenoid valves 80r, 80s, 80t, 80u, 80v are N/C type ON/OFF
solenoid valves in each of which a spool is displaced to the open
position upon being supplied with current (being energized). In an SH-SOL
column of the operation mode table in FIG. 4, the first to fifth solenoid
valves 80r, 80s, 80t, 80u, 80v are indicated by A, B, C, D and E,
respectively.

[0055] An output port of the first solenoid valve 80r is connected to an
operating port 80j1 of the first clutch shift valve 80j to urge a spool
80j2 rightward (in the drawing) against urging force of a spring. An
output port of the second solenoid valve 80s is connected to an operating
port 80k1 of the second clutch shift valve 80k to urge a spool 80k2
rightward against urging force of a spring.

[0056] An output port of the third solenoid valve 80t is connected to an
operating port 80n1 of the first servo shift valve 80n to urge a spool
80n2 rightward against urging force of a spring.

[0057] Similarly, an output port of the fourth solenoid valve 80u is
connected to an operating port 80o1 of the second servo shift valve 80o
to urge a spool 80o2 rightward, while an output port of the fifth
solenoid valve 80v is connected to an operating port 80p1 of the third
servo shift valve 80p to urge a spool 80p2 rightward.

[0059] The fifth linear solenoid valve 80w is of N/C type in which a spool
is displaced to the open position upon being supplied with current (being
energized), while the sixth linear solenoid valve 80x is of N/O
(normally-opened) type in which a spool is displaced to the closed
position upon being supplied with current.

[0060] In an LC column of the operation mode table in FIG. 4, the fifth
linear solenoid valve 80w is indicated by E and in a PL column thereof,
the sixth linear solenoid valve 80x by F. In FIG. 4, the "LC" means the
pressure supplied to the lockup clutch 12d of the torque converter 12 and
the "PL" means the line pressure.

[0061] Returning to the explanation on FIG. 2, an input port 80w1 of the
fifth linear solenoid valve 80w is connected to the aforementioned line
pressure, while a first output port 80w2 thereof is connected to an input
port 80y1 of the LC shift valve 80y and then, through the input port 80y1
and an output port 80y2, connected to an input side of the lockup clutch
12d of the torque converter 12.

[0062] Internal pressure of the torque converter 12 is connected to a
feedback port of the fifth linear solenoid valve 80w. Engagement and
disengagement of the lockup clutch 12d is controlled by the LC shift
valve 80y and degree of engagement (engagement pressure) thereof is
regulated through output pressure of the fifth linear solenoid valve 80w.

[0063] The output ports of the first and second solenoid valves 80r, 80s
are connected not only to the first and second clutch shift valves 80j,
80k but also to operating ports 80y3, 80y4 of the LC shift valve 80y,
respectively, and it makes possible to urge a spool 80y5 leftward (in the
drawing) against urging force of a spring.

[0064] Accordingly, when the first and second solenoid valves 80r, 80s are
deenergized (demagnetized), the spool 80y5 of the LC shift valve 80y is
positioned as illustrated so that the input port 80y1 and output port
80y2 are communicated with each other.

[0065] As a result, LC control pressure outputted from the fifth linear
solenoid valve 80w is supplied to the lockup clutch 12d of the torque
converter 12 through the input port 80y1 and output port 80y2, thereby
engaging the lockup clutch 12d.

[0066] On the other hand, when at least one of the first and second
solenoid valves 80r, 80s is energized (magnetized), the spool 80y5 of the
LC shift valve 80y is displaced leftward in the drawing and, as shown in
FIG. 3, the input port 80y1 is communicated with an output port 80y6.
Consequently, the hydraulic pressure supply to the torque converter 12
(i.e., a piston chamber of the lockup clutch 12d) is stopped and, since
the output port 80y2 is connected to a drain port, the operating oil in
the piston chamber of the lockup clutch 12d is discharged through the
drain port.

[0067] An input port 80x1 of the sixth linear solenoid valve 80x is
connected to the line pressure and an output port 80x2 thereof is, on the
one hand, connected to a second input port 80y7 of the LC shift valve 80y
and then, through the input port 80y7 and an output port 80y 8, connected
to a lubricating system (or a connecting section which is described
later).

[0068] On the other, the output port 80x2 of the sixth linear solenoid
valve 80x is connected to the pressure regulation port 80d1 of the
regulator valve 80d through a hydraulic passage 80a, as clearly shown in
FIG. 3. As a result, the line pressure supplied through the sixth linear
solenoid valve 80x supplies hydraulic pressure (signal pressure) to one
end of a pool 80d2 of the regulator valve 80d through the pressure
regulation port 80d1.

[0069] Thus, it is configured such that, in accordance with a position of
the spool 80d2 that can be displaced in response to the signal pressure
sent after being regulated by the sixth linear solenoid valve 80x, the
regulator valve 80d regulates (decreases) discharged pressure of the
hydraulic pump 80c to further regulate the line pressure.

[0070] The hydraulic passage 80α connecting the output port 80x2 of
the sixth linear solenoid valve 80x and the pressure regulation port 80d1
of the regulator valve 80d is connected via the connecting section (now
assigned by 80γ) with a hydraulic passage 80β connected to the
first output port 80w2 of the fifth linear solenoid valve 80w through the
LC shift valve 80y. The connecting section 80γ is installed with a
selecting mechanism 80δ.

[0071] As shown in FIG. 3, the selecting mechanism 80δ has a ball
valve 80δ1 that is movably housed in an oil chamber having a larger
diameter than inner diameters of the hydraulic passages 80α,
80β.

[0072] The ball valve 80δ1 functions to select the higher-pressure
one between the output pressure of the fifth linear solenoid valve 80w
and that of the sixth linear solenoid valve 80x such that the selected
one acts on the pressure regulation port 80d1 of the regulator valve 80d.

[0073] To be more specific, in the selecting mechanism 80δ, the oil
chamber is connected with the hydraulic passages 80α, 80β so
that they face to each other, while the ball valve 80δ1 is movably
housed in the oil chamber. Owing to the configuration, upon being pressed
by the higher-pressure output between the output pressures of the fifth
and sixth linear solenoid valves 80w, 80x supplied through the hydraulic
passages 80α, 80β, the ball valve 80δ1 can be moved to
obstruct the lower-pressure output side (that faces the higher-pressure
output side). Thus, it is configured to select the higher-pressure output
between the output pressures of the fifth and sixth linear solenoid
valves 80w, 80x, such that the selected one acts on the pressure
regulation port 80d1 of the regulator valve 80d.

[0074] Hence, the output ports of the first and second solenoid valves
80r, 80s are connected not only to the first and second clutch shift
valves 80j, 80k but also to one end of the spool 80y5 through the
operating ports 80y3, 80y4 of the LC shift valve 80y, so that the spool
80y5 is urged leftward (in the drawing) against urging force of a spring.

[0075] As mentioned above concerning the explanation about the hydraulic
pressure supply to the lockup clutch 12d of the torque converter 12, when
the first and second solenoid valves 80r, 80s are both deenergized, the
spool 80y5 of the LC shift valve 80y is positioned as illustrated so that
the input port 80y1 and output port 80y5 are communicated with each
other, whereby the line pressure outputted through the fifth linear
solenoid valve 80w is supplied to the lockup clutch 12d of the torque
converter 12 through the input port 80y1 and output port 80y2.

[0076] On the other hand, when at least one (or both) of the first and
second solenoid valves 80r, 80s is energized, the spool 80y5 of the LC
shift valve 80y is displaced leftward in FIG. 3 so that the input port
80y1 is communicated with the output port 80y6, whereby, as shown in the
drawing, the line pressure transmitted through the fifth linear solenoid
valve 80w is sent from the output port 80y6 to the connecting section
80γ through the hydraulic passage 80β.

[0077] The explanation on FIG. 1 will be resumed. The transmission T has a
shift controller 84. The shift controller 84 is constituted as an
Electronic Control Unit (ECU) having a microcomputer. Further, an engine
controller 86 similarly constituted as an ECU having a microcomputer is
provided to control the operation of the engine 10.

[0078] The shift controller 84 is able to communicate with the engine
controller 86 to acquire information including an engine speed, throttle
opening, AP (Accelerator Pedal) opening, etc., therefrom.

[0079] A first rotational speed sensor 90 is installed near the even input
shaft 14 to produce an output or signal indicative of an input rotational
speed NM of the transmission T, while second, third and fourth rotational
speed sensors 92, 94, 96 are installed at the first and second secondary
input shafts 20, 22 and the output shaft 28, respectively, and each
produces an output or signal indicative of a rotational speed of the
associated shaft. A fifth rotational speed 100 is installed near the
drive shaft 74 to produce an output or signal indicative of a vehicle
speed V.

[0080] First and second pressure sensors 102, 104 are installed at
hydraulic passages connected to the first and second clutches 24, 26 of
the hydraulic pressure supply unit 80 to produce outputs or signals
indicative of pressure (hydraulic pressure) of the operating oil ATF to
be supplied to the first and second clutches 24, 26, respectively.

[0081] A range selector position sensor 106 is provided near a range
selector (not shown) installed at the operator's seat of the vehicle and
produces an output or signal indicative of a range selected from among D,
P, R and N through manipulation by the operator.

[0082] The outputs of the above sensors are all sent to the shift
controller 84. Based on the sensor outputs and information acquired by
communicating with the engine controller 86, the shift controller 84
energizes and deenergizes the first linear solenoid valve 80f, etc., in
accordance with the operation mode table in FIG. 4, thereby controlling
the operation of the transmission T.

[0083] As shown in the operation mode table in FIG. 4, in this embodiment,
the transmission T has four operation modes of A, B, C and D, as follows:

[0084] A: Normal driving (running) in the D range

[0085] B: Driving (running) only with odd-numbered speed in the D range

[0086] C: Driving (running) only with even-numbered speed in the D range

[0087] D: Driving (running) in the R range or parked in the P or N range

[0088] In the foregoing, the modes B and C are given as fail safe modes to
be applied when a failure (abnormality) occurs at the first or second
clutch 24, 26, or the like.

[0089] In FIG. 4, numbers of 1 to 8 labeled beside A, B, C and D in a
vertical row under the "MODE" (operation mode) indicate forward gears of
first to eighth speeds. Letters of A, B, C, D and E in a lateral row
under the "SH-SOL" indicate the first to fifth solenoid valves 80r, 80s,
80t, 80u, 80v as mentioned above, and when a circle (o) is given, it
means to be energized while when a cross (x) is given, it means to be
deenergized, so that the corresponding gear is established. In the same
manner, letters of A, B, C, D, E and F under the "CLUTCH,"

[0090] "SERVO," "LC" and "PL" indicate the first to sixth linear solenoid
valves 80f, 80g, 80h, 80i, 80w, 80x. When one of the letters of A to F is
given, it means that the corresponding valve is energized.

[0091] The fifth and sixth linear solenoid valves 80w, 80x are indicated
by E and F in the LC column and PL column In the PL column, "F or E"
means that the higher-pressure one between the output pressure of the
fifth linear solenoid valve 80x (F) and that of the sixth linear solenoid
valve 80w (E) is applied.

[0092] As for the reverse gear, in the mode A, since it is established
when hydraulic pressure is supplied to the RVS clutch 58 to engage it, no
indication is given. In the modes B, C and D, the reverse gear is not
established when a cross (x) is given and is established when one of the
valves corresponding to the indicated letter, e.g., the second linear
solenoid valve 80g indicated by B is energized.

[0093] As can be clearly seen in FIG. 4, this embodiment is characterized
in that the lockup clutch 12d of the torque converter 12 can be
disengaged with simple structure, while the operation of the transmission
T can be changed among the above four operation modes.

[0094] The change in the operation mode is first explained. When both of
the first and second solenoid valves 80r, 80s are deenergized, the mode A
is established. When the first solenoid valve 80r is deenergized and the
second solenoid valve 80s is energized, the mode B is established, while
in the opposite case thereof, the mode C is established. When both of the
first and second solenoid valves 80r, 80s are energized, the mode D is
established.

[0095] In the mode A, the first and second clutches 24, 26 and the lockup
clutch 12d are all engageable; in the mode B, only the first clutch 24 is
engageable; in the mode C, only the second clutch 26 is engageable; and
in the mode D, none of the three clutches 24, 26, 12d are engageable.

[0096] Based on the output of the range selector position sensor 106, when
a failure does not occur at the first and second clutches 24, 26, the
shift controller 84 energizes and deenergizes the first and second
solenoid valves 80r, 80s to establish the mode A or D, while when a
failure occurs, controlling the valves 80r, 80s to establish the mode C
or D in accordance with the table of FIG. 4.

[0097] In the mode A, the first-third speed synch mechanism 60 is moved
rightward in FIGS. 1 and 2 to connect the first-speed drive gear 32 to
the first secondary input shaft 20 to engage the first clutch 24, so that
the first speed gear is established.

[0098] When the second-fourth speed synch mechanism 64 is moved rightward
in FIGS. 1 and 2 to connect the second-speed drive gear 40 to the second
secondary input shaft 22 to engage the second clutch 26, the second speed
gear is established. The gear is shifted up and down among the first to
eighth speeds by repeating the similar process.

[0099] At this time, a so-called "pre-shift" operation in which, while a
present gear is established, hydraulic pressure is supplied to the synch
mechanism corresponding to the next (target) gear, is carried out. With
this, it becomes possible to shift the gear with uninterrupted driving
force and good response.

[0100] This embodiment is configured to be able to change (select) the
operation mode among the four modes through magnetization and
demagnetization of the first and second solenoid valves 80r, 80s. Owing
to this configuration, it becomes possible to change or select the
operation mode with simple structure, i.e., without the manual valve that
is generally used in this type of hydraulic pressure supply apparatus to
switch a hydraulic passage in response to the operation of a range
selector. Further, since driving of the vehicle in either one of the mode
B and C is possible even when a failure occurs, the required minimum
driving can be ensured.

[0101] Next, the configuration that the lockup clutch 12d of the torque
converter 12 can be disengaged with simple structure will be explained.
In this embodiment, in order to achieve this configuration, the first
output port 80w2 of the fifth linear solenoid valve 80w that controls the
line pressure and supplies it to the lockup clutch 12d of the torque
converter 12 is connected to the LC shift valve 80y, and the operating
ports 80y3, 80y4 of the LC shift valve 80y are connected to at least one
(more exactly, both) of the first and second solenoid valves 80r, 80s
with which the operation mode can be changed.

[0102] Specifically, since some components double as other devices, it
becomes possible to suppress increase in the number of components.
Further, when a failure occurs, the foregoing configuration simply
connects the output port 80y2 of the LC shift valve 80y to the drain
port, so that hydraulic pressure supply to the lockup clutch 12d of the
torque converter 12 can be promptly stopped to disengage the lockup
clutch 12d, thereby reliably avoiding a stall of the engine 10.

[0103] This embodiment is further characterized in that, as explained with
reference to FIG. 3, the hydraulic passage 80α connecting the
output port 80x2 of the sixth linear solenoid valve 80x and the pressure
regulation port 80d1 of the regulator valve 80d is connected via the
connecting section 80γ with the hydraulic passage 80β
connected to the first output port 80w2 of the fifth linear solenoid
valve 80w through the LC shift valve 80y, and the connecting section
80γ is installed with the selecting mechanism 80δ in which
the higher pressure output is selected to act on the pressure regulation
port 80d1 of the regulator valve 80d.

[0104] This will be further explained with reference to FIG. 5 onward.

[0105] FIG. 5 is a set of explanatory views showing the characteristics of
outputs relative to supply current to the valves.

[0106] As mentioned earlier, as a technique described in '213, in order to
supply a predetermined maximum pressure when a solenoid valve used to
control line pressure fails, the solenoid valve is configured to be an
N/O type linear solenoid valve that is opened when a failure occurs so as
to supply the predetermined maximum pressure. Since manufacturing
variance exists in this type of solenoid valve that controls line
pressure, a value covering the variance (called the "variance coverage
value") is always added to a current value to be supplied. Under this
condition, when the maximum value of supply line pressure is increased, a
gain of the line pressure relative to the current value is increased and
fluctuation in hydraulic pressure is also increased, so that the variance
coverage value is needed to be increased.

[0107] In FIG. 5A, solid lines indicate the characteristics of output
pressure (maximum pressure) of the sixth linear solenoid valve 80x and
imaginary lines indicate that when it is assumed that the output pressure
is increased. As illustrated, when the output pressure is increased, a
gain of the output relative to current supplied to a valve is increased
and, consequently, fluctuation in hydraulic pressure becomes larger
relative to current fluctuation in the same current value (command
value), so that control accuracy deteriorates.

[0108] Further, as shown in FIG. 5B, when the output pressure of the sixth
linear solenoid valve 80x is increased, consumption current is increased
in a low line pressure range that is often used when the vehicle cruises.

[0109] In view of the above facts, this embodiment is configured to ensure
driving of the vehicle without a special device even when the sixth
linear solenoid valve 80x that controls the line pressure fails, and
suppress the increase in control margin of the line pressure and in
consumption current.

[0111] Since the fifth linear solenoid valve 80w needs to output
engagement pressure to the lockup clutch 12d of the torque converter 12,
the output pressure thereof is set higher than the maximum output
pressure of the sixth linear solenoid valve 80x used to control the line
pressure.

[0112] Note that the sixth linear solenoid valve 80x should preferably be
of N/O type because it needs to output necessary hydraulic pressure when
failed, while the fifth linear solenoid valve 80w should preferably be of
N/C type so as not to output hydraulic pressure when failed.

[0113] This embodiment is configured to select the higher-pressure one
between the output pressures of the fifth and sixth linear solenoid
valves 80w, 80x, as shown in FIG. 6B.

[0114] Specifically, in a normal range, since the input port 80y1 and
output port 80y2 of the LC shift valve 80y are communicated with each
other, the output pressure of the fifth linear solenoid valve 80w is not
supplied to the selecting mechanism 80δ. However, in the case where
hydraulic pressure is supplied to at least one of the operating ports
80y3, 80y4 of the LC shift valve 80y so that the output port 80y2 and
output port 80y6 are communicated with each other, the output pressures
of the fifth and sixth linear solenoid valves 80w, 80x are sent to the
selecting mechanism 80δ and the higher-pressure one therebetween is
outputted from the selecting mechanism 80δ.

[0115] Therefore, as mentioned in the foregoing, it is configured such
that the selecting mechanism 80δ (ball valve 80δ1) is
provided at the connecting section 80γ at which the hydraulic
passage 80α connecting the sixth linear solenoid valve 80x and the
pressure regulation port 80d1 of the regulator valve 80d and the
hydraulic passage 80β connected to the first output port 80w2 of the
fifth linear solenoid valve 80w are interconnected.

[0116] Further, it is configured such that the fifth linear solenoid valve
80w is connected to the LC shift valve 80y, the operating ports 80y3,
80y4 are connected to the output ports of the first and second solenoid
valves 80r, 80s, and the second output port 80y6 of the LC shift valve
80y is connected to the connecting section 80γ, whereby, at the
connecting section 80γ, the higher-pressure one between the output
pressures of the fifth and sixth linear solenoid valves 80w, 80x is
selected to act on the pressure regulation port 80d1.

[0117] Here, when hydraulic pressure is not supplied from one or any of
the first and second solenoid valves 80r, 80s, the spool 80y5 of the LC
shift valve 80y is positioned as illustrated, so that hydraulic pressure
supplied from the output port 80y6 of the LC shift valve 80y to the oil
chamber of the selecting mechanism 80δ of the connecting section
80γ through the hydraulic passage 80β is zero.

[0118] As a result, the ball valve 80δ1 is positioned in the oil
chamber of the selecting mechanism 80δ as illustrated and
accordingly, the output pressure of the sixth linear solenoid valve 80x
is selected and supplied to the regulator valve 80d.

[0119] In contrast, when hydraulic pressure is supplied from at least one
of the first and second solenoid valves 80r, 80s, the spool 80y5 of the
LC shift valve 80y is displaced so that, as shown in FIG. 3, the input
port 80y1 is communicated with the output port 80y6 while the output port
80y2 is connected to the drain port. Accordingly, the higher-pressure one
between the output pressures of the fifth and sixth linear solenoid
valves 80w, 80x is selected and supplied to the regulator valve 80d.

[0120] Hence, driving of the vehicle can be ensured without a special
device even when the sixth linear solenoid valve 80x that controls the
line pressure fails.

[0121] Further, when the vehicle is moved backward (reverse), since the
lockup clutch 12d is generally disengaged, it is not necessary to use the
fifth linear solenoid valve 80w for engaging the lockup clutch 12d.
Consequently, when it is desired to make the line pressure high in a
limited range such as a reverse range, the fifth linear solenoid valve
80w is utilized for that purpose, so that it becomes possible to reliably
establish the reverse gear and suppress the variance coverage value,
thereby preventing the increase in consumption current.

[0122] To be more specific, since the RVS clutch 58 is smaller in diameter
and the number of friction plates than the first and second clutches 24,
26, the higher line pressure is necessary compared to the first and
second clutches 24, 26. However, since it is configured as above, the
reverse gear can be reliably established.

[0123] As stated above, the embodiment is configured to have an hydraulic
pressure supply apparatus (hydraulic pressure supply unit 80) for a
transmission (T) having an input shaft (12) connected to a drive shaft
(10a) of a prime mover (engine 10) mounted on a vehicle through a torque
converter (12) with a lockup clutch (12a), first and second secondary
input shafts (20, 22) installed in parallel with the input shaft, an
output shaft (28) connected to a wheel (76), first and second clutches
(24, 26) connect the input shaft to the first and second secondary input
shafts upon being supplied with hydraulic pressure, a plurality of pairs
of gear groups (drive gears 32, 34, 36, 38, 40, 42, 44, 46) installed at
the first or second secondary input shaft, and a gear selecting mechanism
(synchronizing mechanisms 60, 62, 64, 66) adapted to select one of the
plurality of the pairs of the gear groups upon being supplied with
hydraulic pressure to establish an odd-numbered speed or even-numbered
speed, the transmission changing an output of the prime mover in speed
through the established speed and transmitting it to the wheel through
the output shaft, comprising: a hydraulic pump (80c) adapted to be driven
by the prime mover and to draw up operating oil (ATF) from a hydraulic
pressure source (reservoir 80a) and discharge the operating oil; a
regulator valve (80d) adapted to regulate discharged pressure discharged
from the hydraulic pump to a line pressure; first and second switching
valves (first and second clutch shift valves 80j, 80k) adapted to supply
hydraulic pressure to the first and second clutches; a first hydraulic
control valve (fifth linear solenoid valve 80w) adapted to supply the
regulated line pressure to the lockup clutch; a third switching valve (LC
shift valve 80y) connected to an output port of the first hydraulic
control valve; and first and second electromagnetic valves (first and
second solenoid valves 80r, 80s) connected to operating ports of the
first, second and third switching valves and adapted to switch among the
first, second and third switching valves upon being energized and
deenergized.

[0124] With this, it becomes possible to promptly and easily disengage the
lockup clutch 12d of the torque converter 12 with simple structure, i.e.,
without a special device, in other words, with the structure that does
not result in high cost. Further, it becomes possible to operate the
transmission T in a range selected by the operator without the manual
valve.

[0125] In the apparatus, one of the first and second electromagnetic
valves is energized and deenergized to change an operation mode of the
transmission among a first operation mode (mode A) in which shifting is
possible with the odd-numbered speed and the even-numbered speed in a
forward range (D), a second operation mode (mode B or C) in which
shifting is possible with the odd-numbered speed or the even-numbered
speed in the forward range, and a third operation mode (mode D) in which
the vehicle is driven in a range (NP, R, N) other than the forward range.

[0126] With this, in addition to the above effects, the operation of the
transmission T can be changed among the three (more precisely, four)
modes only by magnetizing and demagnetizing the first and second
electromagnetic valves (first and second solenoid valves) 80r, 80s.

[0127] In the apparatus, one of the first and second electromagnetic
valves is energized and deenergized to supply hydraulic pressure to the
lockup clutch through the first hydraulic control valve and stop the
supply. With this, in addition to the above effects, the lockup clutch
12d can be easily and promptly disengaged only by magnetizing and
demagnetizing the first and second electromagnetic valves (first and
second solenoid valves) 80r, 80s.

[0128] In the apparatus, the input shaft includes first and second input
shafts (odd-numbered speed input shaft 16 and first secondary input shaft
20; even-numbered speed input shaft 14 and second secondary input shaft
22) connected to the drive shaft of the prime mover through first and
second clutches, respectively, and the output shaft includes at least one
output shaft installed in parallel with the first and second input
shafts, and the transmission includes a dual clutch type automatic
transmission having: a plurality of speeds (first-speed drive gear 32 to
seventh-eighth speed driven gear 54) to be established through gears
installed between the first and second input shafts and the output shaft,
the plurality of the speeds being constituted by at least four sets; a
synchronizing mechanism (60, 62, 64, 66) corresponding to each of the
four sets, adapted to be operated upon being supplied with hydraulic
pressure to move from a neutral position to select one of the speeds that
constitutes a corresponding one of the four sets so as to engage a
corresponding one of the gears to one of the first and second input
shafts and the output shaft; and a hydraulic pressure supply control unit
including first and second pressure regulators (fourth and third linear
solenoid valves 80i, 80h) interposed at a hydraulic pressure circuit
connecting the hydraulic pressure source and the synchronizing mechanism,
each adapted to selectively supply hydraulic pressure to the
synchronizing mechanism to move such that the output of the prime mover
is outputted from one of the first and second input shafts to the output
shaft through the selected speed.

[0129] With this, in addition to the above effects, in the dual clutch
type automatic transmission, it becomes possible to promptly and easily
disengage the lockup clutch 12d of the torque converter 12 with simple
structure, i.e., without a special device. Further, it becomes possible
to operate the transmission T in a range selected by the operator without
the manual valve.

[0130] It should be noted that, in the foregoing, although the dual clutch
type automatic transmission is explained, it is not limited to the
exemplification above and any configuration can be applied.

[0131] It should also be noted that, although the engine (internal
combustion engine) is exemplified as the prime mover, it may be hybrid
combining the engine and an electric motor, or only the motor may be
used.

[0132] Japanese Patent Application No. 2011-121641 filed on May 31, 2011
is incorporated by reference herein in its entirety.

[0133] While the invention has thus been shown and described with
reference to specific embodiments, it should be noted that the invention
is in no way limited to the details of the described arrangements;
changes and modifications may be made without departing from the scope of
the appended claims.

Patent applications by Noriyuki Yagi, Wako-Shi JP

Patent applications by HONDA MOTOR CO., LTD.

Patent applications in class Plural power paths from prime mover

Patent applications in all subclasses Plural power paths from prime mover